Production of circulation interferon in children with varicella

Interferon (IFN) alpha was detected in the serum of children with varicella. The serum IFN was demonstrated in the acute phase of varicella and became negative 7 days after the onset of rash. Serum IFN was detected during the incubation period in two patients tested before the onset of rash. Some correlation was shown between the positive rate of circulating IFN and the severity of illness.

Establishment and characterization of an epithelial cell line, SGE1, from isolated rat renal glomeruli

An epithelial cell line, designated as SGE1, has been established from isolated rat renal glomeruli. SGE1 cells are able to grow continuously in a serum-free medium at similar growth rates to those in the medium containing serum. Quantitative studies of the cells in the serum-free condition demonstrated that SGE1 cells required a collagen type I or IV, fibronectin, or laminin-coated substratum for adhesion and growth, and among them, collagen type I and IV were most effective. Essential medium supplements for the adhesion and growth were epidermal growth factor and transferrin, respectively, and both effects were noticeably enhanced with linoleic acid. Morphological observation found that in a monolayer culture, SGE1 cells formed domes, and in a collagen embedding culture, they formed cystic spheres having features of a simple cuboidal epithelium, polarized formation of microvilli and tight junctions as well as a lateral cell membrane with cytoplasmic projections. In addition, SGE1 cells expressed Fx1A antigens, which are nephritogenic antigens on their microvilli.

Studies on the mesangial handling of protein antigens: influence of size, charge and biologic activity

The influence of certain physicochemical and biologic properties of protein antigens on their handling by the glomerular mesangium was studied in rats. The following ferritin-based probes were employed: (a) naturally occurring ferritin isomers to examine the role of molecular size; (b) chemically cationized ferritins (pI 7.1 and 8.8) to test charge effects; (c) glutaraldehyde (GA-)coupled ferritin as an analogue of a toxic molecule. Molecular size was found to be a major determinant of the extent and rapidity of antigen uptake, but had only a minor influence on persistence. The rapidity of uptake and antigen persistence was charge dependent, but to a limited extent. Biologic activity of macromolecules appears to be a very important determinant of mesangial handling since GA-treated ferritin was taken up much more rapidly and to a greater extent than native ferritin, and could persist for very prolonged periods.

Experimental autoimmune glomerulonephritis with pulmonary hemorrhage in rats. The dose-effect relationship of the nephritogenic antigen from bovine glomerular basement membrane

Experimental autoimmune glomerulonephritis with pulmonary hemorrhage was induced in rats by a single injection of soluble antigen obtained from bovine glomerular basement membrane. Groups of rats were injected with various amounts of the nephritogenic antigen with Freund's complete adjuvant and killed 10 weeks later. Glomerulonephritis with linear deposition of IgG along the glomerular basement membrane developed in 7 of 10 rats injected with 10 micrograms of the antigen and all 20 rats of other 2 groups with 100 or 1,000 micrograms of the antigen. Pulmonary hemorrhage was observed in 21 of 27 rats with nephritis, and it was particularly severe in those injected with 1,000 micrograms. Glomerulonephritis with pulmonary hemorrhage and the linear deposition of IgG along with the glomerular basement membrane suggests that this model resembles human anti-glomerular basement membrane antibody-induced glomerulonephritis including Goodpasture's syndrome. The nephritic rats showed symptoms of nephrotic syndrome such as hypoalbuminemia, hypercholesterolemia and hypertriglyceremia, and the severities of these symptoms clearly depended on the degree of proteinuria.

Isolation and characterization of nephritogenic antigen from bovine glomerular basement membrane

A method for isolation of a potent nephritogenic antigen from bovine glomerular basement membrane has been established; the glomerular basement membrane was solubilized by trypsin digestion and fractionated successively by gel filtration on Ultrogel AcA-34, concanavalin A affinity chromatography and affinity chromatography on immobilized antibodies. The antigen thus prepared was found to be highly nephritogenic; it causes glomerulonephritis in rats by a single injection of 0.1 mg per individual. Amino acid and carbohydrate analyses revealed that the antigen is a glycoprotein which contains amino acids and sugars characteristic of collagen, namely, hydroxyproline, hydroxylysine, glycine, glucose and galactose, although the relative amounts of these amino acids and sugars are less than those found in Type IV collagen of glomerular basement membrane.

Cationic macromolecule-induced nephrotic syndrome in rabbits. Lack of immune complex involvement

Rabbits given a single intravenous injection of highly cationised horse spleen ferritin (isoelectric point greater than 9.5), 2 to 100 mg/kg of body weight, frequently developed glomerulonephritis, and a substantial proportion became nephrotic. The disease usually remitted spontaneously. Renal tissue obtained before onset of proteinuria (by biopsy), during the acute phase and in the phase of remission, was examined for the presence of cationized ferritin, rabbit IgG, and C3 by immunofluorescence. Electron microscopy was performed on material prepared conventionally and after treatment with polyethyleneimine (to visualize fixed anionic sites in the glomeruli). Cationic ferritin molecules initially bound to the fixed anionic sites in the glomerular basement membrane but disappeared before the onset of proteinuria (6 +/- 3 days). Glomerular deposition of rabbit immunoglobulin or complement was not seen, and electron microscopy did not reveal deposits in the glomerular capillary walls. This makes it unlikely that immune complexes play a role in the pathogenesis of the induced disease. The striking features were extensive loss of epithelial foot processes and pronounced loss of negative charge from the glomerular basement membrane and from the epithelial cell surface coat. These changes preceded onset of proteinuria and, by reference to those animals not developing proteinuria, were seen to be closely linked to the subsequent development of proteinuria. It appears that the transient interaction of a cationic, macromolecular protein antigen with the fixed anionic sites in the glomerular basement membrane can set a chain of events in motion that leads to loss of negative charge and epithelial cell withdrawal, ultimately resulting in proteinuria.

Interaction of cationized antigen with rat glomerular basement membrane: in situ immune complex formation

The influence of charge and size on antigen binding to the rat glomerular basement membrane (GBM) was investigated. Chemically cationized ovalbumin, human serum albumin (HSA), human immunoglobulin G (Hu IgG), horse spleen ferritin and human immunoglobulin M (Hu IgM) were injected into rats intravenously. By immunofluorescence significant glomerular binding occurred when the pI exceeded a threshold value of 8.5 to 9.5. At a given pI antigen binding increased with molecular size. Cationized Hu IgM bound only weakly to the glomerular capillary wall, presumably excluded due to size. Subepithelial immune deposits were formed only when antibody was injected subsequently. Detailed electron microscopic studies on in situ formation of immune complexes were performed using cationized horse spleen ferritin. Early on subendothelial deposits were very marked, giving way to subepithelial deposits with time. Under the conditions employed, it appears that deposits can be formed directly at the subepithelial locus but that complexes are also formed subendothelially, dissociating into free molecules or small complexes and then migrating through the lamina densa and reforming.

Quantitative studies of in situ immune complex glomerulonephritis in the rat induced by planted, cationized antigen

Cationized human IgG can bind to the rat glomerular basement membrane (GBM), act as planted antigen, and induce in situ immune complex formation accompanied by severe glomerulonephritis. Perfusion of highly cationized human IgG (isoelectric point {more than} 9.5) via the left renal artery resulted in preferential localization within the perfused kidney (up to 56 percent of dose injected); after intravenous administration, only 4 percent was bound to the kidneys. The planted antigen was localized along the glomerular capillary walls and was accessible for antibody administered intravenously 1 h after perfusion, when virtually no antigen remained in the circulation. Persistence of cationized human IgG in the perfused kidney was markedly prolonged when complexed with antibody; one-half the cationized human IgG was still present after 12 d. There was a difference in the disappearance rates of antigen and antibody, as cationized human IgG was removed faster from the kidney than the antibody, the binding of which remained almost unchanged during the first week. Renal perfusion of a minimum of 20 mug of cationized human IgG, followed by intravenous injection of antibody, regularly induced severe glomerulonephritis with a proteinuria of at least 100 mg/24 h. The degree and the persistence of proteinuria induced depended on the dose of cationized human IgG perfused. Experiments using radiolabeled antigen and antibody showed that after renal perfusion of 20 mug cationized human IgG, 11.1 mug was kidney bound at the time of antibody injection. At the onset of proteinuria, 4.0 mug of antigen and 31.9 mug of anti-human IgG antibody were present in the perfused kidney. Immunofluorescence revealed immune deposits consisting of cationized human IgG and rabbit IgG (anti-human IgG) along the GBM. The staining pattern was linear (confluent) during the first 2 d and became granular during the course of the disease. Electronmicroscopically, a prominent finding was the accumulation of dense deposits, mainly in the subepithelial space and beneath the slit pores.

An approach to postembedding staining of protein (immunoglobulin) antigen embedded in plastic: prerequisites and limitations

A method is described for performing postembedding staining of protein (immunoglobulin) antigen embedded in styrene-methacrylate resin. Fixation of specimens in a combination of 4% paraformaldehyde and 0.2% picric acid and washing in buffer containing 7% sucrose, followed by abrupt dehydration with absolute acetone in the cold preserved the antigenicity, although in a masked form. The masked antigenicity could be reexposed by treatment with nonspecific protease. Staining with fluorescent-, peroxidase-, or ferritin-labeled antibodies on semi- and ultrathin sections resulted in specific localization of the antigen. We applied this technique to the localization of rabbit immunoglobulin in specimens of renal tissue obtained from rats with anti-glomerular basement membrane nephritis; we also localized human IgG in a renal biopsy specimen. The prerequisites for recovery of antigenicity are such that preservation of tissue structure at the light microscopic level is good, but relatively poor at the electron microscopic level.

Anionic binding sites in the glomerular basement membrane: possible role in the pathogenesis of immune complex glomerulonephritis

This paper details the ways in which the anionic sites of the GBM could be involved in immune complex deposition. Experiments were performed with chemically cationised proteins to test the hypotheses proposed. The most detailed investigations were concerned with the role of basic (cationic) antigen as a planted antigen, leading to in situ immune complex formation. A model was developed where it was possible to induce marked proteinuria following a single injection of small quantities of cationised human IgG or ferritin.

The isolation of an optimal small size immunoferritin conjugate fraction

A procedure is described for preparing immunoferritin conjugates consisting of one antibody molecule attached to one ferritin molecule. Results obtained with such a reagent faithfully reflect the true distribution of antigenic determinants, and allow more accurate quantification.

Immunohistological staining of antigens on semithin sections of specimens embedded in plastic (GMA-Quetol 523)

Glycol methacrylate-Quetol 523, introduced by Kushida (1977) for combined light and electronmicroscopy studies at low magnification, also permits application of immunofluorescence methods to semithin sections. To recover the antigenicity of proteins fixed with formaldehyde, abrupt dehydration before embedding and subsequent treatment of the semithin sections with protease were essential. Post-staining with suitable histological stains allows exact correlation of antigen localization with tissue structure.

Immuno-electron microscopic localization of lipopolysaccharide antigens on ultrathin sections of Salmonella typhimurium

Lipopolysaccharide antigens were demonstrated on ultrathin sections of styrene-embedded Salmonella typhimurium by direct postembedding staining with ferritin-labeled antibodies. The antigenicity, partially masked in the embedding process, could be satisfactorily recovered by treatment of ultrathin sections with nonspecific protease. As judged from the reaction site of the ferritin-labeled antibodies, the lipopolysaccharides were localized in two zones. The broader zone of densely distributed ferritin molecules was superimposed over the whole outer cellwall, and a smaller zone revealing antigenicity was found over the cell membrane, which strongly supports the concept that the latter is the site of synthesis of lipopolysaccharides. The well-defined labeled areas between these two antigenic zones may be the routes whereby the synthesized polysaccharide molecules reach the cell wall.

Autoantibody specific for the glomerular mesangium and Bowman's capsule in man

Investigation of serum from a nominally healthy subject revealed an unusual autoantibody with specificity for the glomerular mesangium and Bowman's capsule. Immunofluorescence studies on rodent kidney sections revealed typical mesangial fluorescence and intense linear staining of Bowman's capsule. The antibody was organ, but not species, specific and did not correspond to any previously described antibody with anti-mesangial activity (e.g. anti-actomyosin or anti-fibronectin). Intravenous injection in mice resulted in heavy mesangial deposition of antibody within one hour, the antibody disappeared within 2--4 weeks, and no urinary abnormalities were seen. Retrospective analysis of clinical data revealed a history of chronic hepatitis and possible drug abuse, but no evidence for impaired renal function at any timepoint. To our knowledge this is the first report of specific anti-mesangial antibody in man, the pathogenetic relevance remains unclear.

Comparison of the handling of ferritin and ferritin-protein conjugates by the glomerular mesangium: kinetic studies in the rat

Kinetic studies on the uptake and elimination of ferritin and ferritin-protein conjugates in the rat glomerular mesangium are reported. Ferritin was prepared from horse spleens and conjugates were prepared using either human IgG or albumin. The degree of mesangial uptake was dose dependent and a competitive effect with the reticuloendothelial system was observed. Maximal mesangial fluorescence occurred at a lower dosage with conjugate than with native ferritin. In addition, conjugate persisted for months within the mesangium as compared to a matter of days in the case of ferritin alone. The disappearance of native ferritin from the mesangium paralleled that seen in the circulation. Conjugate, however, disappeared far more rapidly from the circulation than from the mesangium. At a point in time when the mesangium still contained conjugate but the blood was negative, rabbit antiserum to ferritin was injected and was observed to deposit in the mesangium. This demonstrated the accessibility of mesangially sequestered antigen to circulating antibody. This system provides a model for long term studies on the effect of immune reactions occurring in the mesangium.

Effect of antibody avidity on the induction of renal injury in anti-glomerular basement membrane nephritis

Antibodies to glomerular basement membrane (GBM) of the rat could be fractionated according to their avidity by elution from trypsin-digested GBM (bound to Sepharose) with increasing concentrations of KSCN. The percentage of kidney-fixing antibody in each fraction and the degree of proteinuria induced as determined 24 h after injection increased with the avidity of the antibody fraction when equal doses were administered.

Masking of protein antigen by modification of amino groups with carbobenzoxychloride (benzyl chloroformate) and demasking by treatment with nonspecific protease

Cryostat sections of various substrates were treated with carbobenzoxychloride in acetone to modify antigens. By applying specific fluorescent antibodies, it could be shown that the antigenic determinants of rabbit gamma-globulin and bovine insulin were totally masked. The antigenicity of ACTH was markedly reduced, whereas the polysaccharide antigens of Salmonella typhimurium were only partially masked. After masking, antigenicity could be restored by treatment with nonspecific protease. The reversible protection of amino groups by carbobenzoxychloride may be a way to preserve protein antigens during embedding in plastics, as such materials also bind to amino groups, blocking the antigenicity of proteins.